1. Field of the Invention
The present invention relates to manufacturing management, and in particular to a system and method of pull-in planning and control with a fixed planning schedule for an order.
2. Description of the Related Art
Supply chain is important for modern enterprises, systemizing purchase of materials, transformation of materials into intermediate and finished products, and distribution of finished products. In the supply chain, customers transmit requests (demands) consisting of a request for a particular quantity of a product by a specific date to a manufacturer, and the manufacturer plans its manufacturing schedule according to these received requests to satisfy each customer.
Supply chain management has become an important issue to meet the goals of reduced inventory and increased productivity. Conventionally, resources and facilities of a production system are regarded as limiting factors. Therefore, not every customer request may be met, since some may be promised, some may suffer inadequate supply, and others rejected. Consequently, effective demand and capacity management in supply chain management without excess capacity loss has become fundamental and critical for most manufacturing and distribution organizations.
Supply chains exist in both service and manufacturing organizations, although the complexity of the chain may vary greatly from industry to industry and firm to firm. For integrated circuit (IC) foundries, the manufacturing process of each IC product is complicated and varies and the cost of wafers and capacity is relatively high.
Many commercial supply chain solution providers provide packaged systems for clients to install and follow, such as i2 technology or ADEXA Inc. For a manufacturer or a factory, customers assign forecast demands prior to seasons or months. Commercial supply chain providers usually provide a demand planning engine to allocate demand in further production. A production scheduling engine is also embedded in the commercial supply chain systems to arrange resources and materials for a production plan when a customer decides to purchase an order from the foundry. The production scheduling engine provides a master production schedule (MPS) for the manufacturer or factory to follow. However, conventional production scheduling engines are designed to meet the best interests of the manufacturer or factory. More specifically, conventional production scheduling engines are programmed to generate a minimum-cost, optimal-capacity, and low-inventory MPS.
For IC foundries, conventional production scheduling engines recalculate and generate an updated MPS to optimize resources and capacity when receiving new orders. When lots are running (hereinafter referred to as work-in-process), the MPS is still changed, indicating rolling production schedules for running lots for optimization of foundry resources. It becomes difficult to promise delivery of the lots because of the rolling MPS.
In addition, customers sometimes submit pull-in orders, for many reasons. For example, if a customer has booked a capacity to fabricate an order of a product in December, but, due to high demand for the product on the market, the customer decides to prioritize the order for delivery in mid-September, it will be difficult for the foundry to promise which day or week in September that they can deliver the pull-in order because of the rolling MPS. Conventional planning engines continually update the MPS of the pull-in order, making it difficult to provide the customer with an exact delivery date. For customers, the uncertainty will disrupt transport and inventory planning and management.
In addition, the rolling MPS encourages customer pull-in behavior. Since the foundry is unable to deliver the order with a commit date by the conventional rolling MPS plan engine, customers tend to place the pull-in order prior to their original demand to prevent delivery delay. The pull-in behavior can be severely detrimental to the production system because it changes the original demand planning and can cause production disorder when many orders are unexpectedly changed to pull-in status.